Lead has been used in many industries for decades. For instance, lead is widely used for radiation shielding applications due to its efficiency and low cost. While efficient and low-cost, lead has been found to be toxic to animals, and particularly toxic to humans.
In response to the desire to reduce toxicity or the use of toxic compounds, and in order to comply with state, federal, and international regulations regarding the use, transport, and disposal of lead and lead-containing composite materials, numerous lead substitutes and lead-free composite materials have been developed as replacements for lead or lead-filled composite materials. Lead substitutes and lead-free composite materials can be used in a variety of applications including, but not limited to, ammunition, construction, and radiation shielding applications.
While lead-free composite materials developed for use in radiation shielding applications thus far may offer the benefit of reduced or no toxicity, lead-free composite materials containing certain fillers in certain amounts detrimentally affect the composite material. For example, at certain levels of filler content, viscosity becomes so high that the ability to cast the material is reduced or lost completely. Some fillers also detrimentally affect the resistance to arcing and/or the dielectric strength of the composite material. A lead-free, non-toxic composite material having suitable dielectric strength and arc resistance properties and being efficient in radiation protection, economical to make and use as well as easily handled and castable or processed by other methods, such as liquid phase sintering, is desired.